Hereditary Chiari Malformation

I'm pretty new here, but I posted last week that my son had a mri for headaches he has been having for about 4-5 years. The mri report said he had cerebellar tonsilar ectopia of 3-5 mms below the foramina magnum but said mri was normal. The nurse at the neurologist office also told me the mri was normal. I had an mri done also due to chronic neck pain and headaches (which was previously diagnosed as tension headaches) and my mri report just said mild cerebellar tonsilar ectopia without evidence of hydrocephalus or pressure on the brainstem. It was read by a different radiologist who did notput any measurments. When I started researching Chiari last week, I remember reading that there was some evidence that this could possible be hereditary, what are your opinions? Also, does this mean my other kids should be tested even if they don't have symptoms or should it wait til they actually have symptoms?

there is some research done that Chiari does run in families....find a new neurologist and get copies of both yours and your sons MRI's and reports!